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Keep floating
The largest of the four varieties of the Portuguese man of war known as a pneumatophore is a
single body and supports the rest of the colony by keeping the
colony afloat. This pear shaped sac may measure slightly more than
15 centimeters in length. It has a pleasing blue color and may in
addition sport some stripes in red or pink. It is a living thing in
its own right and it secretes enough air to keep itself afloat. It
has a muscular body, the contractions of which result in the body’s
floating. The course it takes is determined by the curvature of the
float and on the underwater resistance of the rest of the colony.
Nature has provided it with a sail on top of the muscular bladder to
assist in floating.
The food procurers
The dactylozooids are the polyps whose responsibility is to detect
and capture food using their tentacles and convey the captured food
to the polyps that digest it for the rest of the colony. And this is
a job that they perform continuously. Their long tentacles are
forever fishing and once they come into contact with some food, the
muscles in the tentacles contract and drag the prey to where the
polyps that have to digest them can reach them easily.
The tentacles are easily the most striking part of the Portuguese
man-of-war. These trailing tentacles may reach a length of 30 meters.
The sting of these tentacles can evoke mild to harsh symptoms that
sometimes need medical attention. This is because the tentacles have
thousands of poison secreting cells known as nematocysts. The toxin
secreted by the nematocysts is a mixture of several enzymes and is
potent enough to disable small prey. At times, even tentacles that
have been separated from the main body are capable of stinging with
the same intensity. Analysis has shown the toxin produced for the
sting to be a neurotoxin and it is estimated to be almost as potent
as cobra venom.
The stomach
Those who perform the digestive role are the gastrozooids. These
gastrozooids respond very quickly to the presence of food. When in a
state of rest, they measure hardly 2 millimeters. But once they
sense the presence of food, they expand to more than 20 millimeters
to encircle the food. To digest the food thus captured, they secrete
various enzymes that break down the proteins, carbohydrates and fats
present in the food and turn it into a form that is easily absorbed
by the colony. Favorite food consists of small crustaceans and
other surface plankton. The food is shared by the whole colony
through interconnecting digestive cavities.
The nursery
And then there are the gonozooids who carry on the reproductive
process. The Portuguese man-of-war is a hermaphrodite and therefore
each gonozooid has both male and female characteristics. Fertilized
eggs released by the gonozooids develop into large colonies.
Stranded specimens may be found on beaches and it is safest to keep
out of water if floating colonies have been seen. |
